Yolk sac tumors of the mediastinum with prominent spindle cell features: a clinicopathologic study of three cases

Primary germ cell tumours of the mediastinum: A review with emphasis on diagnostic challenges

This article will review current aspects of the histopathological, immunohistochemical and molecular analysis of primary mediastinal germ cell tumours (PMGCTs) as well as their aetiological, epidemiological, clinical and therapeutic features. PMGCTs represent an important differential diagnosis in the spectrum of mediastinal tumours, and their diagnosis is usually made on small tissue samples from core needle biopsies in combination with diagnostic imaging and serum tumour markers. As in lymphomas, a small biopsy is often the only viable tumour sample available from these patients, as they receive chemotherapy prior to eventual surgical resection. Pathologists therefore need to apply an efficient combination of immunohistochemical markers to confirm the diagnosis of a PMGCT and to exclude morphological mimics.

Combined Thymic Epithelial Neoplasms - a Review

Thymic epithelial neoplasms are the most common tumors of thymic origin but are overall rare in the general population. Their morphologic diversity, ranging from low grade to overtly malignant lesions, along with various histologic growth patterns make them a diagnostically challenging group of tumors. Very occasionally, thymomas and thymic carcinomas may develop in combination with other benign or malignant lesions of thymic origin, further complicating the diagnostic process. The focus of this review lies on the spectrum of thymic epithelial tumors that present with other thymic lesions in the same tumor mass, such as multilocular thymic cysts, neuroendocrine neoplasms, lymphomas, and germ cell tumors among others. Awareness of the existence of such unusual tumors may not only aid in their diagnosis but may also have implications for prognostic and therapeutic purposes.

Primary mediastinal germ cell tumors

Mediastinal germ cell tumors share similar histopathological, immunohistochemical, and molecular features with their counterparts in the gonads. Therefore, proper clinical and radiological evaluation of patients with an anterior mediastinal mass becomes essential in the final interpretation of these tumors. The gold standard for the diagnosis of these tumors remains histopathological evaluation. However, immunohistochemical stains and molecular studies also provide an aid in cases in which the histology is not typical. It is also important to keep in mind that a small mediastinoscopic biopsy may not be representative of the entire neoplasm. In this review, we will provide our perspective regarding histopathological diagnosis, staging, immunohistochemical and molecular profile, and briefly family of tumors address pertinent epidemiological, clinical and treatment options. However, the main emphasis is to review the process of pathological assessment in pre and post-treated tumors. Knowledge of the different growth patterns and histological associations is important, mainly when confronted with mediastinoscopic biopsies, which ultimately will determine treatment options.

Mediastinal Germ Cell Tumors: A Review and Update on Pathologic, Clinical, and Molecular Features

Mediastinal germ cell tumors (MGCTs) are the most common extragonadal germ cell tumors (GCTs) and most often arise in the anterior mediastinum with a male predilection. MGCTs also have a predilection for patients with Klinefelter syndrome and possibly other genetic conditions. MGCTs, as GCTs at other extragonadal sites, are thought to arise from germ cells improperly retained during migration along the midline during embryogenesis. Similar to their counterparts in the testes, MGCTs are classified into seminomatous and nonseminomatous GCTs. Seminomatous MGCT represents pure seminoma, whereas nonseminomatous MGCTs encompass pure yolk sac tumors, embryonal carcinoma, choriocarcinoma, mature or immature teratoma, and mixed GCTs with any combination of GCT types, including seminoma. Somatic-type or hematologic malignancies can also occur in association with a primary MGCT. MGCTs share molecular findings with GCTs at other sites, most commonly the presence of chromosome 12p gains and isochromosome i(12p). Treatment includes neoadjuvant chemotherapy followed by surgical resection of residual tumor, with the exception of benign teratomas, which require only surgical resection without chemotherapy. In this review, we highlight and provide an update on pathologic, clinical, and molecular features of MGCTs. Immunohistochemical profiles of each tumor type, as well as differential diagnostic considerations, are discussed.

A Case of Urachal Yolk Sac Tumor With Spontaneous Rupture in a Child

Tumors arising from urachus in children are exceedingly rare and sporadically reported in literature. Being a midline structure, the urachus may harbor neoplastic germ cell elements and can occasionally present as a case of acute abdomen. A 20-month-old toddler presented with spontaneous rupture of an urachal yolk sac tumor causing hemoperitoneum. He underwent resection, received platinum-based chemotherapy and presently remains well on follow-up. Despite its rarity, urachal germ cell tumors must be considered in a child with acute abdomen and tumor markers must be measured preemptively in such cases.

[Neurogenic spindle-cell tumors of the mediastinum: two cases]

INTRODUCTION

Neurogenic tumors can develop from neural cells in any location. They are commonly found, however, in the mediastinum, most often in its posterior compartment. Neurogenic tumors can be benign or malignant. In the anterior compartment, they must be distinguished from their differential diagnoses.

CASES

We report one case of a malignant peripheral nerve sheath tumor in the posterior mediastinum of a 29-year-old man and another of a schwannoma of the anterior mediastinum, in an 82-year-old woman.

DISCUSSION

Neurogenic tumors of spindle-shaped cells in the mediastinum are generally benign, but can be malignant. Often asymptomatic, they are usually detected on standard pulmonary radiography, but computerized tomography is necessary, supplemented by magnetic resonance imaging, especially for posterior mediastinal tumors, to provide additional information and to assess its possible extension to adjacent structures. Radiographic, clinical, and especially histopathological features are essential for diagnosis.

Mediastinal germ cell tumors

Germ Cell Tumors (GCT) represent an important group of mediastinal tumors. Because of genetic characteristics and behavior have been divided in prepubertal and postpubertal tumors, and their origin remains controversial. The genetic changes are diverse, but the most frequent is i (12p), and can be associated to gonadal disgenesis. Histological classification is similiar to that of gonadal tumors and all histological types have been described in the mediastinum. Teratomas may undergo malignant transformation with the emergence of somatic tumors such as haematological malignancies, sarcomas, carcinomas and neurogenic tumors, and such transformation may occur in the primary site or in the metastases. Prognostic factors in mediastinal germ cell tumors include: age of the patient, histological type, distant metastases, stage, status of resection, level of serum tumor markers and proliferation markers. Immunohistochemistry is especially useful when the primary GCT is occult, to separate types of immature GCT, and to determine the lineage of malignant transformation which may be important to design treatment strategies.

Anterior mediastinal nonseminomatous germ cell tumor with malignant transformation: a case report

OBJECTIVE

We report a case of a 21-year-old man who presented with the unusual symptoms of heart failure and was found to have an anterior mediastinal yolk sac tumor.

METHODS

A review of the literature using the Ovid search engine was performed.

RESULTS

The patient was treated with the current standard of neoadjuvant chemotherapy: bleomycin, etoposide, and cisplatin (BEP) with marked reduction in tumor size, followed by en bloc surgical resection. The final pathology revealed teratoma with malignant change: chondrosarcoma, adenocarcinoma, and poorly differentiated sarcoma.

CONCLUSIONS

This is a rare initial presentation of an anterior mediastinal germ-cell tumor with treatment consisting of neoadjuvant therapy and surgical resection. In addition, we present the adverse and extremely rare malignant degeneration of this tumor.

Primary yolk sac tumor of the urachus

Pure yolk sac tumor is the most common malignant gonadal tumor of infants and toddlers. However, the majority of extragonadal germ cell tumors in the midline are either seminomas (germinomas) or teratomas, and pure yolk sac tumors account for only a small fraction of these lesions. To date, only 1 primary urachal pure yolk sac tumor has been reported in the literature. We describe another case, occurring in a 7-month-old male infant who presented with a rapidly enlarging intra-abdominal tumor with marked engorgement of the superficial venous plexus around the umbilicus. With periodic follow-up for 3 years following surgical extirpation of the tumor and adjuvant chemotherapy, this patient is still alive without evidence of disease. Notably, the glandular elements predominating in the frozen sections resulted in the initial misdiagnosis of the tumor as a urachal adenocarcinoma, although the entirely resected specimen revealed typical histologic patterns and Schiller-Duval bodies. Immunohistochemistry showed that the tumor cells were diffusely reactive to alpha-fetoprotein, alpha(1)-antitrypsin, and cytokeratin. Tumor cells were negative for p53 protein, but revealed overexpression for MDM2 protein. Flow cytometry demonstrated a diploid DNA content with S-phase being as high as 55.36%. This case emphasizes that pure yolk sac tumor can occur primarily in the remnant of the urachus in young children.

Mediastinal non-seminomatous germ cell tumours: their association with non-germ cell malignancies

Mediastinal non-seminomatous germ cell tumors are unique tumors in that they are associated with both sarcomatous and hematologic neoplasms. This paper relates our experience at Indiana University with these tumors, and discusses the possible mechanisms of their occurrence, especially with respect to the hematologic neoplasms.

Fine-needle aspiration cytology of a mediastinal seminoma associated with multilocular thymic cyst

Multiloculated thymic cysts are uncommon lesions that can be either acquired or associated with malignancies. This report describes the fine-needle aspiration (FNA) cytology of a mediastinal seminoma with prominent cystic change, confirmed by surgical pathology examination and ancillary studies performed on both the cytology and tissue specimens. The FNA cytology revealed clusters of malignant oval-to-polygonal-shaped cells with large oval nuclei possessing prominent nucleoli set in a pale-to-eosinophilic cytoplasm. These cells were surrounded by a dense lymphoid infiltrate along with a few noncaseating granulomas. The large malignant seminoma cells stained positive for placental alkaline phosphatase (PLAP) and negative for both low molecular and broad-spectrum cytokeratin. The differential diagnosis of malignancies associated with thymic cysts is presented. To the best of our knowledge, this is the first report of aspiration cytology of a mediastinal seminoma associated with a multilocular cyst.